<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>组合选择器</title>
    <style>
        /*后代选择器*/

    </style>
</head>
<body>
    <div class="top">
        <ol>
            <li>aa</li>
            <li>bb</li>
        </ol>
    </div>

    <div class="aaa">
        <ol>
            <li>11</li>
            <li>22</li>
        </ol>
    </div>
</body>
</html>